Orthodontic devices are used to treat irregularities in teeth and jaws. For patients with minor irregularities braces are sufficient to correct these issues. Often however, the use of braces as a lone treatment is not sufficient. In the common case of crowding, a palatal expander is needed to widen the upper and lower jaws to improve the fit between the upper and lower teeth, and to make space for any irregularly crowded teeth.
Palate expansion can be classified into two categories of expansion: slow and rapid expansion. Slow expansion expands the palate at a rate of 0.5 to 1 mm per week as is associated with greater stability and permanency.
A commonly used device for slow palatal expansion is the Kloehn face bow. The face bow and variations are shown in U.S. Pat. Nos. 721,655, 3,036,380, 3,111,758, 3,137,841, 3,311,978, 3,314,151, and 3,429,044. In general, the Kloehn face bow includes an inner bow which attaches inside a patient's mouth to a patient's molar teeth and an outer bow outside of the mouth that is attached to an external strap to be worn around a patient's head or neck.
When expanding, the inner arch wire of the Klohen tips the crowns buccally. The outer bow and pull of the neck straps tip the crowns lingually. Ultimately, one effect cancels the other, resulting in a bodily lateral expansion force. The large, well anchored, tripod roots of the first molars offer more than enough anchorage to cause the mid-palatal suture to grow. This well-established method results in a molar anchorage that is 75-80% efficient. For improved expansion results, it is desirable to increase the molar anchorage efficiently.
U.S. Pat. No. 4,212,637 sought to improve the safety of the device by creating a Kloehn like device with an outer bow that was separable from the inner bow. However, with the outer bow being capable of being removed, it is possible that a user of this device may choose to not to wear the outer bow, decreasing compliance as well as the efficiency of the device. Thus, it is desirable to have a more attractive device that increases compliance and simultaneously maintains proper anchorage efficiency, thus making it an overall more efficient device.
It is also known in the art to provide auxiliary wires 7-10 mm from each end of the arch wire to provide an additional anchoring location of the arch wire and prevent rotation and tipping of the attached molars.